Audio equalization of audio environment

ABSTRACT

An example method of operation may include determining a frequency response to a measured chirp signal detected from one or more speakers, determining an average value of the frequency response based on a high limit value and a low limit value, subtracting a measured response from a target response, and the target response is based on one or more filter frequencies; determining a frequency limited target filter with audible parameters based on the subtraction, and applying an infinite impulse response (IIR) biquad filter based on an area defined by the frequency limited target filter to equalize the frequency response of the one or more speakers.

TECHNICAL FIELD

This application generally relates to customized alternative automatedtuning for a networked audio system.

BACKGROUND

In a workplace, conference area, public forum or other environment, theaudio producing speakers and the audio capturing microphones may bearranged in a networked configuration that covers multiple floors, areasand different sized rooms. Tuning the audio at all or most locations haspresented a challenge to the manufacturers and design teams of suchlarge-scale audio systems. More advanced tuning efforts, such ascombining different test signal strategies and independent speakersignals present further challenges to the setup and configurationprocesses.

In one example, a test process may initiate a tone via one speaker and acapturing process via one or more microphones, however, the multitude ofspeakers may not be accurately represented by testing a single speakersignal and identifying the feedback of that speaker when other speakerswill be used during an announcement, presentation or other auditoryevent.

In a typical audio system, such as a conference room, there may bemicrophones, speakers, telephony integration, input signal processing,output signal processing, acoustic echo cancellation, noise reduction,non-linear processing and mixing of audio signals. Because of thecomplexity of the corresponding equipment, the installation process andthe software configurations, an expert team of persons are required tosetup and test and install all the audio equipment.

SUMMARY

One example embodiment may provide a method that includes one or more ofidentifying a plurality of separate speakers on a network controlled bya controller, providing a first test signal to a first speaker and asecond test signal that includes a different frequency than the firsttest signal to a second speaker, detecting the different test signals atone or more microphones, automatically tuning the speaker outputparameters based on an analysis of the different test signals.

Another example embodiment includes a process configured to perform oneor more of identifying, in a particular room environment, a plurality ofspeakers and one or more microphones on a network controlled by acontroller and amplifier, providing test signals to play sequentiallyfrom each amplifier channel of the amplifier and the plurality ofspeakers, monitoring the test signals from the one or more microphonessimultaneously to detect operational speakers and amplifier channels,providing additional test signals to the plurality of speakers todetermine tuning parameters, detecting the additional test signals atthe one or more microphones controlled by the controller, andautomatically establishing a background noise level and noise spectrumof the room environment based on the detected additional test signals.

Another example embodiment may include an apparatus that includes aprocessor configured to perform one or more of identify, in a particularroom environment, a plurality of speakers and one or more microphones ona network controlled by a controller and amplifier, provide test signalsto play sequentially from each amplifier channel of the amplifier andthe plurality of speakers, monitor the test signals from the one or moremicrophones simultaneously to detect operational speakers and amplifierchannels, provide additional test signals to the plurality of speakersto determine tuning parameters, detect the additional test signals atthe one or more microphones controlled by the controller, andautomatically establish a background noise level and noise spectrum ofthe room environment based on the detected additional test signals.

Yet another example embodiment may include a non-transitory computerreadable storage medium configured to store instructions that whenexecuted cause a processor to perform one or more of identifying, in aparticular room environment, a plurality of speakers and one or moremicrophones on a network controlled by a controller and amplifier,providing test signals to play sequentially from each amplifier channelof the amplifier and the plurality of speakers, monitoring the testsignals from the one or more microphones simultaneously to detectoperational speakers and amplifier channels, providing additional testsignals to the plurality of speakers to determine tuning parameters,detecting the additional test signals at the one or more microphonescontrolled by the controller, and automatically establishing abackground noise level and noise spectrum of the room environment basedon the detected additional test signals.

Still yet another example embodiment may include a method that includesone or more of identifying a plurality of speakers and microphonesconnected to a network controlled by a controller, assigning apreliminary output gain to the plurality of speakers used to apply testsignals, measuring ambient noise detected from the microphones,recording chirp responses from all microphones simultaneously based onthe test signals, deconvolving all chirp responses to determine acorresponding number of impulse responses, and measuring average soundpressure levels (SPLs) of each of the microphones to obtain a SPL levelbased on an average of the SPLs.

Still yet another example embodiment includes an apparatus that includesa processor configured to identify a plurality of speakers andmicrophones connected to a network controlled by a controller, assign apreliminary output gain to the plurality of speakers used to apply testsignals, measure ambient noise detected from the microphones recordchirp responses from all microphones simultaneously based on the testsignals, deconvolve all chirp responses to determine a correspondingnumber of impulse responses, and measure average sound pressure levels(SPLs) of each of the microphones to obtain a SPL level based on anaverage of the SPLs.

Still yet another example embodiment includes a non-transitory computerreadable storage medium configured to store instructions that whenexecuted cause a processor to perform one or more of identifying aplurality of speakers and microphones connected to a network controlledby a controller, assigning a preliminary output gain to the plurality ofspeakers used to apply test signals, measuring ambient noise detectedfrom the microphones, recording chirp responses from all microphonessimultaneously based on the test signals, deconvolving all chirpresponses to determine a corresponding number of impulse responses, andmeasuring average sound pressure levels (SPLs) of each of themicrophones to obtain a SPL level based on an average of the SPLs.

Still yet another example embodiment may include a method that includesone or more of determining a frequency response to a measured chirpsignal detected from one or more speakers, determining an average valueof the frequency response based on a high limit value and a low limitvalue, subtracting a measured response from a target response, whereinthe target response is based on one or more filter frequencies,determining a frequency limited target filter with audible parametersbased on the subtraction, and applying an infinite impulse response(IIR) biquad filter based on an area defined by the frequency limitedtarget filter to equalize the frequency response of the one or morespeakers.

Still yet another example embodiment includes an apparatus that includesa processor configured to determine a frequency response to a measuredchirp signal detected from one or more speakers, determine an averagevalue of the frequency response based on a high limit value and a lowlimit value, subtract a measured response from a target response,wherein the target response is based on one or more filter frequencies,determine a frequency limited target filter with audible parametersbased on the subtraction, and apply an infinite impulse response (IIR)biquad filter based on an area defined by the frequency limited targetfilter to equalize the frequency response of the one or more speakers.

Still yet another example embodiment includes a non-transitory computerreadable storage medium configured to store instructions that whenexecuted cause a processor to perform one or more of determining afrequency response to a measured chirp signal detected from one or morespeakers, determining an average value of the frequency response basedon a high limit value and a low limit value, subtracting a measuredresponse from a target response, wherein the target response is based onone or more filter frequencies, determining a frequency limited targetfilter with audible parameters based on the subtraction, and applying aninfinite impulse response (IIR) biquad filter based on an area definedby the frequency limited target filter to equalize the frequencyresponse of the one or more speakers.

Still yet another example embodiment includes a method that includes oneor more of applying a set of initial power and gain parameters for aspeaker, playing a stimulus signal via the speaker, determining a soundlevel at a microphone location and a sound level at a predefineddistance from the speakers, determining a gain at the microphonelocation based on a difference of the sound level at the microphonelocation and the sound level at the predefined distance from thespeaker, and applying the gain to the speaker output.

Still yet another example embodiment includes an apparatus that includesa processor configured to apply a set of initial power and gainparameters for a speaker, play a stimulus signal via the speaker,determine a sound level at a microphone location and a sound level at apredefined distance from the speakers, determine a gain at themicrophone location based on a difference of the sound level at themicrophone location and the sound level at the predefined distance fromthe speaker, and apply the gain to the speaker output.

Still yet another example embodiment includes a non-transitory computerreadable storage medium configured to store instructions that whenexecuted cause a processor to perform applying a set of initial powerand gain parameters for a speaker, playing a stimulus signal via thespeaker, determining a sound level at a microphone location and a soundlevel at a predefined distance from the speakers, determining a gain atthe microphone location based on a difference of the sound level at themicrophone location and the sound level at the predefined distance fromthe speaker, and applying the gain to the speaker output.

Still yet another example embodiment includes a method that includes oneor more of initiating an automated tuning procedure, detecting via oneor more microphones a sound measurement associated with an output of aone or more speakers at two or more locations, determining a number ofspeech transmission index (STI) values equal to a number of microphones,and averaging the speech transmission index values to identify a singlespeech transmission index value.

Still yet another example embodiment includes an apparatus that includesa processor configured to initiate an automated tuning procedure, detectvia one or more microphones a sound measurement associated with anoutput of a one or more speakers at two or more locations, determine anumber of speech transmission index (STI) values equal to a number ofmicrophones, and average the speech transmission index values toidentify a single speech transmission index value.

Still yet another example embodiment includes a non-transitory computerreadable storage medium configured to store instructions that whenexecuted cause a processor to perform one or more of initiating anautomated tuning procedure, detecting via one or more microphones asound measurement associated with an output of a one or more speakers attwo or more locations, determining a number of speech transmission index(STI) values equal to a number of microphones, and averaging the speechtransmission index values to identify a single speech transmission indexvalue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a controlled speaker and microphone environmentaccording to example embodiments.

FIG. 2 illustrates a process for performing an automatic tuningprocedure in the controlled speaker and microphone environment accordingto example embodiments.

FIG. 3 illustrates a process for performing an automated equalizationprocess in the controlled speaker and microphone environment accordingto example embodiments.

FIG. 4 illustrates an audio configuration used to identify a level ofgain in the controlled speaker and microphone environment according toexample embodiments.

FIG. 5 illustrates an audio configuration used to identify a soundpressure level (SPL) in a controlled speaker and microphone environmentaccording to example embodiments.

FIG. 6A illustrates a flow diagram of an auto-tune procedure in thecontrolled speaker and microphone environment according to exampleembodiments.

FIG. 6B illustrates a flow diagram of another auto-tune procedure in thecontrolled speaker and microphone environment according to exampleembodiments.

FIG. 7 illustrates another flow diagram of an auto-configurationprocedure in the controlled speaker and microphone environment accordingto example embodiments.

FIG. 8 illustrates a flow diagram of an auto-equalization procedure inthe controlled speaker and microphone environment according to exampleembodiments.

FIG. 9 illustrates a flow diagram of an automated gain identificationprocedure in the controlled speaker and microphone environment accordingto example embodiments.

FIG. 10 illustrates a flow diagram of an automated speechintelligibility determination procedure in the controlled speaker andmicrophone environment according to example embodiments.

FIG. 11 illustrates a system configuration for storing and executing theautomatic tuning procedure.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generallydescribed and illustrated in the figures herein, may be arranged anddesigned in a wide variety of different configurations. Thus, thefollowing detailed description of the embodiments of at least one of amethod, apparatus, non-transitory computer readable medium and system,as represented in the attached figures, is not intended to limit thescope of the application as claimed, but is merely representative ofselected embodiments.

The instant features, structures, or characteristics as describedthroughout this specification may be combined in any suitable manner inone or more embodiments. For example, the usage of the phrases “exampleembodiments”, “some embodiments”, or other similar language, throughoutthis specification refers to the fact that a particular feature,structure, or characteristic described in connection with the embodimentmay be included in at least one embodiment. Thus, appearances of thephrases “example embodiments”, “in some embodiments”, “in otherembodiments”, or other similar language, throughout this specificationdo not necessarily all refer to the same group of embodiments, and thedescribed features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

In addition, while the term “message” may have been used in thedescription of embodiments, the application may be applied to many typesof network data, such as, packet, frame, datagram, etc. The term“message” also includes packet, frame, datagram, and any equivalentsthereof. Furthermore, while certain types of messages and signaling maybe depicted in exemplary embodiments they are not limited to a certaintype of message, and the application is not limited to a certain type ofsignaling.

A launch process for establishing an automated tuning and configurationsetup for the audio system may include a sequence of operations. In theauto-configuration phase, system firmware may use Ethernet basednetworking protocols to discover the peripheral devices attached to acentral controller device. These peripherals may include beam-trackingmicrophones, amplifiers, universal serial bus (USB) and Bluetooth (BT)I/O interfaces, and telephony dial-pad devices. Device firmware thenmodifies its own configuration and the configuration of the discoveredperipherals to associate them with one another and to route theassociated audio signals through appropriate audio signal processingfunctions. The auto-tuning phase has three sub-phases, microphone (mic)and speaker detection, tuning, and verification.

Not every amplifier output channel (not shown) managed by a controllerdevice may have an attached speaker. In the microphone and speakerdetection phase, a unique detection signal is played sequentially out ofeach amplifier channel. The input signals detected by all microphonesare simultaneously monitored during each detection signal playback.Using this technique, unconnected amplifier output channels areidentified, and the integrity of each microphone input signal isverified. During the tuning phase, other unique test signals are playedsequentially out of each connected amplifier output channel. Thesesignals are again monitored simultaneously by all microphones. Havingprior knowledge of the microphones' frequency response(s), and usingvarious audio processing techniques, the firmware can calculate thebackground noise level and noise spectrum of the room, sensitivity(generated room SPL for a given signal level) of each amplifier channeland connected speaker, a frequency response of each speaker, a distancefrom each microphone to each speaker, room reverberation time (RT60),etc. Using these calculations, the firmware is able to calculate tuningparameters to optimize per-speaker channel level settings to achieve thegiven target SPL, per-speaker channel EQ settings to both normalize thespeaker's frequency response and achieve the target room frequencyresponse. Acoustic echo cancellation (AEC), noise reduction (NR) andnon-linear processing (NLP) settings which are most appropriate andeffectual for the room environment.

The verification phase occurs after the application of the tuningparameters. During this phase the test signals are again playedsequentially out each connected amplifier output channel and monitoredsimultaneously by all microphones. The measurements are used to verifythe system achieves the target SPL and the system achieves the targetroom frequency response. During the verification phase a speciallydesigned speech intelligibility test signal is played out all speakersand monitored by all microphones simultaneously. Speech intelligibilityis an industry standard measure of the degree to which sounds can becorrectly identified and understood by listeners. Most of themeasurements taken and settings applied by auto-setup are provided in aninformative report for download from the device.

Example embodiments provide a system that includes a controller orcentral computer system to manage a plurality of microphones andspeakers to provide audio optimization tuning management in a particularenvironment (e.g., workplace environment, conference room, conferencehall, multiple rooms, multiple rooms on different floors, etc.).Automated tuning of the audio system includes tuning various soundlevels, performing equalization, identifying a target sound pressurelevel (SPL), determining whether compression is necessary, measuringspeech intelligibility, determining optimal gain approximations to applyto the speakers/microphones, etc. The environment may include multiplemicrophones and speaker zones with various speakers separated by varyingdistances. Third party testing equipment is not ideal and does notprovide simplified scalability. Ideally, identifying the networkcomponents active on the network and using only those components tosetup an optimized audio platform for conferencing or other presentationpurposes would be optimal for time, expertise and expense purposes.

An automated equalization process may be capable of automaticallyequalizing the frequency response of any loudspeaker in any room to anydesired response shape which can be defined by a flat line and/orparametric curves. The process may not operate in real-time during anactive program audio event, but rather during a system setup procedure.The process considers and equalizes the log magnitude frequency response(decibels vs. frequency) and may not attempt to equalize phase. Theprocess may identify optimal filters having a frequency response thatclosely matches the inverse of the measured response in order to flattenthe curve, or reshape the curve to some other desired response value.The process may use single-biquad infinite impulse response (IIR)filters which are bell-shaped to boost or cut a parametric filter,low-pass, and/or high-pass filter. FIR filters could also be used, butIIR filters have optimized computational efficiency and low-frequencyresolution, and are better suited for spatial averaging, or equalizingover a broad listening area in a room.

When performing the equalization process, a desired target frequencyresponse is identified. Typically, this would be a flat response with alow frequency roll-off and high frequency roll-off to avoid designing afilter set which would be attempting to achieve an unachievable resultfrom a frequency-limited loudspeaker(s). The target mid-band responsedoes not have to be flat, and the process permits any arbitrary targetfrequency response in the form of an array of biquad filters. Theprocess also permits a user to set a maximum dB boost or certain cutlimits on the total DSP filter set to be applied prior to any automatedtuning process.

FIG. 1 illustrates a controlled speaker and microphone environmentaccording to example embodiments. Referring to FIG. 1 , the illustrationdemonstrates an audio-controlled environment 112 which may have anynumber of speakers 114 and microphones 116 to detect audio, play audio,replay audio, adjust audio output levels, etc., via an automated tuningprocedure. The configuration 100 may include various different areas130-160 separated by space, walls and/or floors. The controller 128 maybe in communication with all the audio elements and may include acomputer, a processor, a software application setup to receive andproduce audio, etc. In this example, a chirp response measurementtechnique may be used to acquire a frequency response by measurement ofa loudspeaker.

With regard to a setup process, a launch option (auto setup+auto tuning)on the front of a user interface of a user device in communication withthe controller 128 may provide a way to test the sound profile of theroom(s), the speaker(s) and microphone(s). Network discovery can be usedto find devices plugged-in and included in a list of system devices andprovide them with a baseline configuration to initiate during operation.The audio system may be realized in a graphical format during a devicediscovery process, the operator can then drag and drop data for a morecustomizable experience or reset to a factory default level. If thesystem did not adequately tune to a certain level, then an alert can begenerated and any miswirings can be discovered as well by a testingsignal sent to all known devices.

The audio environments normally include various components and devicessuch as microphones, amplifiers, loudspeakers, DSP devices, etc. Afterinstallation, the devices need to be configured to act as an integratedsystem. The software application may be used to configure certainfunctions performed by each device. The controller or central computingdevice may store a configuration file which can be updated during theinstallation process to include a newly discovered audio profile.

One approach to performing the automated tuning process may includepermitting the auto-tune processes to operate on a device that alsocontains custom DSP processing. To enable this combined feature, thecode would discover the appropriate signal injection and monitoringpoints within the custom configuration. With the injection andmonitoring points identified, any selected DSP processing layout wouldbe automatically compatible. Some operations in the auto-tune processwill send test signals out of each speaker one at a time, whichincreases total measurement time when many speakers are present. Otheroperations may include sending test signals out of all speakers in asimultaneous or overlapping time period and performing testing processeson the aggregated sound received and processed.

To reduce a total measurement time, different signals may be played outof each speaker simultaneously. Some different ways to offer mixedsignals may include generating one specific sine wave per speaker wherea unique frequency is used for each different speaker, playing a shortmusical composition where each speaker plays a unique instrument in themix of a music composition, or just tones which are different infrequency can be paired with each speaker, respectively. With a largenumber of speakers, a song with a large variety of percussioninstruments could be used, with one drum sound per speaker. Any othermultichannel sound mixture could be used to drive the process of dynamicand/or customized sound testing. There are other sound event detectionalgorithms that are capable of detecting the presence of a sound in amixture of many other sounds that could be useful with this testinganalysis procedure. The auto-tune could be a combination of voiceprompts and test signals played out of each speaker. The test signalsare used to gather information about the amplifiers, speakers, andmicrophones in the system, as well as placement of those devices in anacoustic space.

There are other signals that could be used to collect the same room andequipment information gathered for testing. The decision to usedifferent signals could be based on different goals, such as signalsused which are pleasant sounding, which may include voice and/or musicprompts. The upside is the elimination of scientific-sounding test tonesbeing played into the space. The potential downside is additional timerequired to extract room and equipment information from less-than-idealsource signals. To reduce the total measurement time, the voice promptscould be eliminated and basic test signals could be used which producethe fastest results.

An auto equalization procedure (see FIG. 3 ) is capable of automaticallyequalizing the frequency response of any loudspeaker in any room to anydesired response shape which can be defined by a flat line and/orparametric curves. The procedure may not be real-time during an activeprogram audio event, but rather during a system setup procedure. Theprocedure equalizes the log magnitude frequency response (decibelsversus frequency) and may not equalize phase. The procedure identifies aset of optimal filters having a frequency response that closely matchesthe inverse of the measured response to flatten or reshape the responseto some other desired response value. The procedure uses single-bi-quadIIR filters which are a bell type (e.g., boost or cut parametricfilter), low-pass, or high-pass. FIR filters could be used, but IIRfilters have a more optimal computational efficiency, low-frequencyresolution, and are better suited for spatial averaging and/orequalizing over a broad listening area in a room.

When performing the equalization process, first a desired targetfrequency response is identified. Typically, this would be a flatresponse with a low frequency roll-off and high frequency roll-off toavoid the process from designing a filter set which would be attemptingto achieve an unachievable result from a frequency-limited loudspeaker.The target mid-band response does not have to be flat, and the procedurepermits any arbitrary target frequency response in the form of an arrayof bi-quad filters. The procedure also permits the user to set a maximumdB boost or to cut limits on the total DSP filter set to be applied.

One example procedure associated with an auto-setup procedure (see FIG.2 ), may provide sequencing through each speaker output channel andperform the following operations for each output: ramping-up a multitonesignal until the desired SPL level is detected, determining if speakeroutput channel is working normally, determining if all microphone (mic)input channels are working normally, setting preliminary output gain forunknown amp and speaker for test signals, measuring ambient noise fromall mics to set base for an RT60 measurement, which is a measure of howlong sound takes to decay by 60 dB in a space that has a diffusesound-field, and checking for excessive noise, providing a chirp testsignal, recording chirp responses from all ‘N’ mics simultaneously intoan array, deconvolving all chirps from ‘N’ mics giving ‘N’ impulseresponses, and for each mic input: locating a main impulse peak andcomputing a distance from speaker to mic, computing a smoothed logmagnitude frequency response and applying mic compensation value (usingknown mic sensitivity), computing a SPL average over all frequencies,averaging frequency response of all mics to obtain a spatial average,performing auto-equalization on the spatial averaged response to match atarget response, the SPL level and distance from nearest and furthestmics is used to compute room attenuation, using the SPL level from anearest mic and room attenuation to compute output gain to achievedesired level at an average distance from all mics, calculating a SPLlimiter threshold, with auto EQ and auto gain engaged, producing a chirpto measure and verify the response, measuring octave-band RT60 for eachmic, and measuring an average SPL from each mic, then averaging all micsto obtain achieved SPL level.

Another example embodiment may include an auto-setup procedure thatincludes determining which input mics are working and which outputspeaker channels are working, performing an auto equalization of eachoutput speaker channel to any desired target frequency response (definedby parametric EQ parameters), auto-setting each output path gain toachieve a target SPL level in the center of the room determined byaverage distance from speaker to microphones, auto-setting of outputlimiters for maximum SPL level in the center of the room, auto-settingof auto-echo cancellation (AEC), non-linear processing (NLP) and noisereduction (NR) values based on room measurements, measuring a frequencyresponse of each output speaker channel in the room, measuring a finalnominal SPL level expected in the center of the room from each outputchannel, measuring an octave-band and full-band reverberation time ofthe room, measuring of noise spectrum and octave-band noise for eachmicrophone, measuring of the noise criteria (NC) rating of the room, andmeasuring of the minimum, maximum, and average distance of all mics fromthe speakers, and the speech intelligibility of the room. All themeasurement data may be used to establish the optimal speaker andmicrophone configuration values.

In one example audio system setup procedure, a launch operation (i.e.,auto setup+auto tuning) on a user interface may provide a way toinitiate the testing of the sound profile of the room, speakers andmicrophones. Network discovery can be used to find devices plugged-inand to be included in a list of system devices and provide them withbaseline configurations to initiate during an audio use scenario. Theaudio system may be realized in a graphical format during a devicediscovery process, the operator can interface with a display and dragand drop data for a more customizable experience or reset to a factorydefault level before or after an automated system configuration. If thesystem did not adequately tune to a certain level, then an alert can begenerated and any miswirings can be discovered as well by a testingsignal sent to all known devices.

The audio environments normally include various components and devices,such as microphones, amplifiers, loudspeakers, digital signal processing(DSP) devices, etc. After installation, the devices need to beconfigured to act as an integrated system. The software of theapplication may be used to configure certain functions performed by eachdevice. The controller or central computing device may store aconfiguration file which can be updated during the installation processto include a newly discovered audio profile based on the currenthardware installed, an audio environment profile(s) and/or a desiredconfiguration. In one example embodiment, an automated tuning proceduremay tune the audio system including all accessible hardware managed by acentral network controller. The audio input/output levels, equalizationand sound pressure level (SPL)/compression values may all be selectedfor optimal performance in a particular environment.

During automated setup, a determination of which input mics are working,and which output speaker channels are working is performed. Theauto-equalization of each output speaker channel is performed to adesired target frequency response (defined by parametric EQ parameters,high pass filters, low pass filters, etc.). A default option may be a“flat” response. Additional operations may include an automated settingof each output path gain to achieve a user's target SPL level in thecenter on the room assuming an average distance of mics, and an autosetting of output limiters for a user's maximum SPL level in the centerof the room. Another feature may include automatically determiningauto-echo cancellation (AEC), non-linear processing (NLP) and NRD valuesbased on room measurements. The following informative measurements whichmay also be performed include a measurement of frequency response ofeach output speaker channel in the room, a measurement of a finalnominal SPL level expected in the center of the room from each outputchannel, a measurement of octave-band reverberation time (RT-60) of theroom, and a measurement of a noise floor in the room. Additionalfeatures may include a measurement of the minimum, maximum, and averagedistance of all mics from the speakers. Those values may provide theinformation necessary to perform additional automatic settings, such assetting a beamtracking microphone's high-pass filter cutoff frequencybased upon the reverberation time in the lower bands of the room, andfine tuning AEC's adaptive filter profile to best match the expectedecho characteristics of the room. The information obtained can be savedin memory and used by an application to provide examples of the acousticfeatures and sound quality characteristics of a conference room. Certainrecommendations may be used based on the room audio characteristics toincrease spacing between mics and loudspeakers, or, to acousticallyadjust a room via the speakers and microphones due to excessive RT-60(reverberance “score” for predicted speech intelligibility)

The audio setup process may include a set of operations, such as pausingany type of conferencing audio layout capability and providing the input(microphone) and output (loudspeaker) control to the auto setupapplication. Sequentially, each output loudspeaker which participates inthe auto-setup will produce a series of “chirps” and/or tones designedto capture the acoustic characteristics of the room. The number ofsounds produced in the room is directly related to the number of inputsand outputs which participate in the auto-setup process. For example, ina system with three microphones and two loudspeakers, auto-setup wouldperform the following actions: (—First Loudspeaker —), loudspeaker 1produces a series of sounds which are captured by mic 1, loudspeaker 1produces a series of sounds which are captured by mic 2, and loudspeaker1 produces a series of sounds which are captured by mic 3; (—NextLoudspeaker —), loudspeaker 2 produces a series of sounds which arecaptured by mic 1, loudspeaker 2 produces a series of sounds which arecaptured by mic 2, loudspeaker 2 produces a series of sounds which arecaptured by mic 3, and after this process completes, the regularconferencing layout audio processing is restored. The gain andequalization for each loudspeaker is adjusted based on auto setupprocessing, AEC performance is tuned for the room based on auto setupprocessing, microphone LPF is tuned for the room based on the auto setupprocessing, and the acoustic characteristics of the room have beenlogged. Optionally, the user is presented with some summarizing datadescribing the results of the auto setup process. It is possible thatthe auto setup may “fail” while processing, if a defective microphone orloudspeaker is discovered, or if unexpected loud sounds (e.g., streetnoise) is captured while the processes is underway. Auto setup will thenhalt, and the end user will be alerted if this is the case. Also, afriendly auto setup voice may be used to discuss with the user what autosetup is doing as it works through the process.

FIG. 2 illustrates an automated equalization process, which includes aniterative process for multiple speakers in the environment. Referring toFIG. 2 , during a boot-up procedure, a user interface may be used tocontrol the initiation and “auto-tune” option. A memory allocationoperation may be performed to detect certain speakers, microphones, etc.The identified network elements may be stored in memory. A tuneprocedure may also be performed which causes the operations of FIG. 2 toinitiate. Each speaker may receive an output signal 202 that is input204 to produce a sound or signal. An ambient noise level may beidentified 206 as well from the speakers and detected by themicrophones. Multiple tones may be sent to the various speakers 208which are measured and the values stored in memory. Also, a chirpresponse 210 may be used to determine the levels of the speakers and thecorresponding room/environment. The impulse responses 212 may beidentified and corresponding frequency response values may be calculated214 based on the inputs. Also, the speech intelligibility rating may becalculated (speech transmission index (STI)) along with the ‘RT60’ valuewhich is a measure of how long sound takes to decay by 60 dB in a spacethat has a diffuse sound-field, meaning a room large enough thatreflections from the source reach the mic from all directions at thesame level. An average of the input values 216 may be determined toestimate an overall sound value of the corresponding network elements.The averaging may include summing the values of the input values anddividing by the number of input values.

Continuing with the same example, an auto-equalization may be performed218 based on the spatial average of the input responses. Theauto-equalization levels may be output 222 until the procedure iscompleted 224. When the outputs are completed 224, the output values areset 226 which may include the parameters used when outputting audiosignals to the various speakers. The process continues iterativelyduring a verification procedure 230, which may include similaroperations, such as 202, 204, 210, 212, 214, 216, for each speaker.Also, in the iterative verification process, a measure of speechintelligibility may be performed until all the output values areidentified. If the outputs are not complete in operation 224, theauto-equalization level 225 is used to continue on with the next outputvalue (i.e., iteratively) of the next speaker and continuing until allspeaker outputs are measured and stored.

The auto-setup operations rely on measurements of loudspeakers,microphones, and room parameters using chirp signals and possible chirpdeconvolution to obtain the impulse response. Chirp signal deconvolutionmay be used acquire quality impulse responses (IRs), which are free ofnoise, system distortion, and surface reflections, using practical FFTsizes. One item which will affect the effectiveness of the auto-setupprocedure is how much is known about system components such asmicrophones, power amps, and loudspeakers. Whenever component frequencyresponses are known, corrective equalization should be applied by thedigital signal processor (DSP) prior to generating and recording anychirp signals in order to increase the accuracy of the chirpmeasurements.

An auto-equalization procedure may be used to equalize the frequencyresponse values of any loudspeaker in any room to a desired responseshape (e.g., flat line and/or parametric curves). Such a procedure mayutilize single-biquad IIR filters of a bell shape type. The process maybegin with a desired target frequency response with a low frequencyroll-off and a high frequency roll-off to avoid encountering limitationson filters established for a particular loudspeaker and room. A targetresponse (H_(target)) may be flat with a low frequency roll-off. Usingthe chirp stimulus/response measurement, the measured frequency responseof a loudspeaker in a room may be obtained. The response needs to benormalized to have an average of 0 dB, high and low frequency limits maybe used to equalize and set limits for the data utilized. The procedurewill compute the average level between the limits and subtract thisaverage level value from the measure response to provide a responsenormalized at ‘0’ (H_(meas)). The frequency-limited target filter isthen determined by subtracting the measured response from the targetresponse: H_(targfilt)=H_(target)−H_(meas) and this value is the targetresponse used for the next auto EQ biquad filter.

To find parametric filters to fit the curve for the H_(targfit), all theimportant curve features (0 dB crossing points and peak points) arefound by a function called FindFreqFeatures( ).

The filter choice at two frequency limits is handled slightly different.If the target filter calls for a boost at the frequency limit, then aPEQ boost filter will be used with its center frequency at the limitfrequency. If the target filter calls for an attenuation at thefrequency limit, which typically happens when the target response has aroll-off, then a HPF/LPF is selected and a −3 dB corner frequency iscomputed to match to point where the curve is −3 dB. This was found toproduce a better match when traversing outside of the auto EQ range,particularly when roll-off responses are desired which will most oftenbe the case. Once all the frequency features of the target filter havebeen identified, a function called FindBiggestArea( ) is used to findthe most salient biquad filter for the target which is characterizedsimply by the largest area under the target filter curve as shown below.

Based on the characteristics, a function calledDeriveFiltParamsFromFreqFeatures( ) computes the 3 parameters (fctr, dB,Q) based on the curve center frequency, dB boost/cut, and the bandwidth(Q). Bandwidth for a 2-pole bandbass filter is defined asfctr/(f_(upper)−f_(lower)) where f_(upper) and f_(lower) are where thelinear amplitude is 0.707*peak. Here there are bell filters which are1+bandpass, but empirically it was found that using 0.707*peak(dB),where the baseline is 0 dB, also provided optimal results for estimatingthe Q of the bell shape. The edge frequencies are not used to calculatethe PEQ bandwidths, but rather are used to delineate two adjacent PEQpeaks. If the area represents an attenuation at a frequency limit, thenthe function will compute a LPF/HPF filter corner frequency where theresponse is −3 dB. From these filter parameters, the auto EQ biquadfilter coefficients are computed and the biquad is added to the auto EQDSP filter set. This updated DSP filter response (H_(dspfilt)) is thenadded to the measured response (H_(meas)) {all quantities in dB} to showwhat the auto-equalized response would look like (H_(autoeq)). Theauto-equalized response (H_(autoeq)) is then subtracted from the targetresponse (H_(target)) to produce a new target filter (H_(targfilt)).This new target filter represents the error, or difference between thedesired target response and the corrected response.

FIG. 3 illustrates a process for determining an automated equalizationfilter set to apply to a loudspeaker environment according to exampleembodiments. Referring to FIG. 3 , the process may include defining atarget response as a list of biquad filters and HPF/LPF frequencies 302,measuring a chirp response from a microphone 304, normalizing the valueto 0 dB between the frequency limits 306, subtracting a measuredresponse from a target response to provide a target filter 308, findinga target filter zero crossings and derivative zeros 310, combining thetwo sets of zero frequencies in a sequential order to identify frequencyfeature values 312, identifying a largest area under the target filtercurve 314, deriving parameters to fit a bell shaped area for frequenciesat 0.707 multiplied by a peak value 316, determining whether the filterparameters are audible 318, if so, the process continues withcalculating the biquad coefficients based on the identified filterparameters 320. The process continues with limiting the filter dB basedon amplitude limits 322, adding this new limited filter to a DSP filterset 324, adding the unlimited EQ filters to a measured response toprovide an unlimited corrected response 326, and subtracting thiscorrected response from the target response to provide a new targetfilter 328. If all available biquads are used 330 then the process ends322, or if not, the process continues back to operation 310.

In order to determine which loudspeaker (speaker) outputs are live, afive-octave multitone (five sinewave signals spaced one octave apart)signal level is applied to the speakers and ramped-up at a rapid ratefor quick detection of any connected live speaker. The multitone signallevel is ramped-up one speaker at a time while the signal level from allmicrophones is monitored. As soon as one microphone (mic) receives thesignal at the desired audio system sound pressure level (SPL) targetlevel (i.e., SPL threshold level), then the multitone test signal isterminated and the speaker output channel is designated as being live.If the multitone test signal reaches a maximum ‘safe limit’ and no micshave received the target SPL level, then the speaker output isdesignated as dead/disconnected. The received five-octave signal ispassed through a set of five narrow bandpass filters. The purpose of thefive octave test tones and five bandpass filters is to prevent falsespeaker detection from either broadband ambient noise, or a single toneproduced from some other source in the room. In other words, the audiosystem is producing and receiving a specific signal signature todiscriminate this signal from other extraneous sound sources in theroom. The same five-octave multitone used to detect live speaker outputsis simultaneously used to detect live microphone inputs. As soon as thehighest mic signal reaches the audio system target SPL level, then themultitone test signal is terminated. At that instant, all mic signallevels are recorded. If a mic signal is above some minimum thresholdlevel, then the mic input is designated as being a live mic input,otherwise it is designated as being dead/disconnected.

In order to set loudspeaker output gain levels, a desired acousticlistening level in dBs for the SPL will be determined and stored infirmware. The DSP loudspeaker output channels will have their gains setto achieve this target SPL level. If the power amplifier gains areknown, and the loudspeaker sensitivities are known, then these outputDSP gains can be set accurately for a particular SPL level, based on,for example, one meter from each loudspeaker (other distances arecontemplated and may be used as alternatives). The level at certainestimated listener locations will then be some level less than thisestimated level. In free space, sound level drops by 6 dB per doublingof distance from the source. For typical conference rooms, the levelversus doubling of distance from a source may be identified as −3 dB. Ifit is assumed each listener will be in the range of 2 meters to 8 metersfrom the nearest loudspeaker, and the gains are set for the middledistance of 4 meters, then the resulting acoustic levels will be within+/−3 dB of the desired level. If the sensitivity of the loudspeaker(s)are not known, then the chirp response signal obtained from the nearestmicrophone will be used. The reason for the nearest microphone is tominimize reflections and error due to estimated level loss versusdistance. From the level and time-of-flight (TOF) of this response, theloudspeaker sensitivity can be estimated, although the attenuation dueto loudspeaker off-axis pickup is not known. If the power amp gain isnot known, then a typical value of 29 dB will be used which mayintroduce an SPL level error of +/−3 dB.

Analyzing electro-acoustic sound systems to identify gains that shouldbe used to achieve optimal acoustic levels. Voltage, power and acousticlevels and gains can be derived from any sound system. Those values canbe used to provide a SPL level at some specific location using a DSPprocessor. In general, an audio system will have a microphone,loudspeaker, a codec, a DSP processor and an amplifier.

FIG. 4 illustrates an example configuration for identifying variousaudio signal levels and characteristics according to exampleembodiments. Referring to FIG. 4 , the example includes a particularroom or environment, such as a conference room with a person 436estimated to be approximately one meter from a loudspeaker 434. Theattenuation values are expressed as gain values. For example,G_(PS)=L_(P)−L_(SPKR) which is the gain from the loudspeaker at onemeter to the person, which may be approximately, for example, −6 dB.L_(P) is the acoustic sound pressure level without regard to anyspecific averaging, L_(SPKR) is the sound pressure value 1 meter fromthe speaker. G_(MP) is the gain from the microphone 432 to the personand GMs is the gain from the microphone to the loudspeaker. A poweramplifier 424 may be used to power the microphone and the DSP processor422 may be used to receive and process data from the microphone toidentify the optimal gain and power levels to apply to the speaker 434.Identifying those optimal values would ideally include determining theG_(PS) and the G_(PS). This will assist with achieving a sound level atthe listener position as well as a set DSP output gain and input preampgain values.

In this example of FIG. 4 , if a few basic parameters are known aboutthe microphone, the amplifier and the loudspeaker, theL_(sens,mic,(1)PA) (dBu) is the sensitivity of an analog mic in dBu asan absolute quantity relative to 1 Pascal (PA), which in this example is−26.4 dBu, the G_(amp) is the gain of the power amp, which in thisexample is 29 dB and the L_(sens,spkr), which is the sensitivity of theloudspeaker, which is in this example is 90 dBa. Continuing with thisexample, the L_(gen) is the level of the signal generator (dBu),G_(dsp,in) is the gain of the DSP processor input including mic preampgain, in this example 54 dB, G_(dsp,out) is the gain of the DSPprocessor output gain, in this example −24 dB. A stimulus signal isplayed and the response signal is measured, which may be, for example14.4 dBu, and L_(1PA)=94. In this example, the sound level at themicrophone may be identified byL_(mic)=L_(dsp)−L_(sens,mic,1PA)+L_(1PA)−G_(dsp.in)=14.4−(−26.4)+94=80.8dBa. For 1 meter from the loudspeaker, the sound level isL_(spkr)=L_(gen)+G_(dsp+)G_(amp+)L_(sens,spkr)−L_(sens,spkr,volts)=0(−24 dB)+29 dB+90 dBa−11.3 dBu=83.7 dBu. GMs can now becalculated=L_(mis)−L_(spkr)=−2.9 dBa. The estimated values would bebased on −2.5 dB per doubling of distance in a typical conference room.

In the event that the gains and other parameters of the mic, power ampand loudspeaker are not known, the measures of L_(p) and L_(mic) aretypically −38 dBu for the mic, with a +/−12 dB, 29 dB+/−3 dB for a poweramp and 90 dBa+/−5 dB for a loudspeaker. The above-noted formulas arenecessary to compute DSP gains for desired sound levels and to achieve adynamic range. The desired listener level L_(P) can then be identifiedby the various gain measurements.

FIG. 5 illustrates a process for identifying a sound pressure level(SPL) in the controlled speaker and microphone environment according toexample embodiments. Referring to FIG. 5 , the example includes alistener 436 in a simulated model being a distance D_(P) from a speaker534 in a particular room. The acoustic level attenuation per doubling ofdistance in free space is 6 dB. However, in rooms this attenuation levelwill be some value less than 6 dB due to reflections and reverberation.A typical value for acoustic level attenuation in conference rooms isabout 3 dB of attenuation per doubling of distance, where generallysmall and/or reflective rooms will be some quantity less than this, andlarge and/or absorptive rooms will be greater than this value.

Producing a desired SPL at a specific location using multiple mics atsome desired listener level L_(P) at some distance D_(P) from aloudspeaker 534, a known level L₁ at 1-meter from the loudspeaker 534,and knowing the attenuation per doubling of distance, and theloudspeaker's sensitivity. All of those parameters can be determinedfrom one chirp at two simultaneous measurement locations shown as D1 andD2. The attenuation per doubling of distance can be calculated from anytwo measurements (at two different locations) in a room assuming theroom uniformly attenuates levels. This assumption is more valid as theroom size increases, and/or becomes more diffuse. This assumption isalso more valid as an average attenuation over all frequencies. Theequation for attenuation per doubling of distance can be derived and as:α_(dd)=−(L₁−L₂)/log 2(D₂/D₁), where L=SPL level, D=distance, and α_(dd)is a negative quantity in this example where attenuation values areconsidered negative gains. The positions L₁ and L₂ from the loudspeakercan be any order (i.e., it is not necessary that D2>D1). Next theloudspeaker sensitivity must be measured, which is the SPL level ‘1’meter from the speaker when driven by a given reference voltage. If ameasurement is made at some distance other than 1 m from the speaker,then that level would be calculated 1 m from the speaker by using α_(dd)and the “doublings of distance” relative to 1 m. The doublings ofdistance from 1 m can be calculated using the expressionOneMeterDoublings=log 2(D₁). Now the level which would occur at 1 m canbe calculated using L_(1 m)=L₁−OneMeterDoublings*αdd. If the electricaltest signal used was the speaker's sensitivity electrical referencelevel, typically 2.83V (1 W at 8 ohms), then L_(1 m)=L_(sens,spkr).However, if the speaker drive voltage was something different, thenL_(sens,spkr) can simply be calculated using the equationL_(sens,spkr)=L_(1 m)−L_(dsp,FSout)−G_(dsp,out)−G_(amp)−G_(attn,out)+L_(sens,spkr,volts).L_(sens,spkr) is the sensitivity of the loudspeaker, L_(dsp,Fsout) isthe sensitivity of the DSP processor output, G_(dsp,out) is the gain ofthe DSP output, G_(amp) is the gain of the power amp and G_(attn,out) isthe gain of any attenuator and L_(sens,spkr,volts) is the sensitivity ofthe loudspeaker in volts.

Now that α_(dd) is identified for the room and the speaker'ssensitivity, the speaker drive level (or DSP output gain) necessary toproduce a desired level L_(P) at the listener distance D_(P) can bedetermined by calculating the one meter doublings to the listenerlocation using: OneMeterDoublings=log 2(D₁). Next the listener level canbe calculated 1 m from the loudspeaker:L_(1 m)=L₁−OneMeterDoublings*α_(dd). Finally, the loudspeaker drivelevel, or DSP output gain, can be identified by:G_(dsp,out)=L_(1 m)−L_(sens,spkr)−L_(dsp,FSout)−G_(amp)−G_(attnout)+L_(sens,spkr,volts).

In the example of FIG. 5 , a room has a loudspeaker on one end and inorder to calculate the DSP output gain required to produce a desired SPLlevel, for example, 72.0 dBSPL at a location 11.92 meters from theloudspeaker. This SPL level is broadband and unweighted, so anunweighted full-range chirp test signal is used. The room happens tohave two microphones, but their distances from the loudspeaker are notyet known, and the loudspeaker is not known. The known system parametersare: L_(dspFSout)=+20.98 dBu, G_(dsp,out)=−20.27 dB (DSP output gain forthe chirp measurement), G_(amp)=29.64 dB, G_(attn,out)=−19.1 dB, andL_(sens,spkr,volts)=+11.25 dBu (2.83 V). The procedure is outlined inseven operations, 1) generate a chirp and measure the response at two ormore locations. Generating a single chirp and recording the responsesfrom the two mics. The chirp measurement reveals the following data:L₁=82.0 dB_(SPL) at 1.89 m from the loudspeaker, L₂=73.8 dB_(SPL) at7.23 m from the loudspeaker, 2) calculate the room attenuation perdoubling of distance, αdd=−(82.0 dB−73.8 dB)/log 2(7.23 m/1.89 m)=−4.24dB/doubling, 3) calculate the chirp level 1 meter from the speaker byfirst finding the closest mic's doubling of distance relative to 1 m,OneMeterDoublings=log 2(1.89 m)=0.918 doublings, now calculate the chirplevel at 1 m using L_(1 m)=82.0 dB_(SPL)−(0.918 doublings)*(−4.24dB/doubling)=85.9 dB_(SPL), 4) calculate the loudspeaker's sensitivity,L_(sens,spkr)=85.9 dB_(SPL)−20.98 dBu−(−20.27 dB)−29.64 dB−(−19.1dB)+11.25 dBu=85.9 dB_(SPL), 5) calculate the doublings from 1 meter tothe listener distance DP, OneMeterDoublings=log 2(11.92 m)=3.575doublings, 6) calculate the level required at 1 meter from theloudspeaker using L1 m=72 dB_(SPL)−(3.575 doublings)*(−4.236dB/doubling)=87.15 dB_(SPL). Finally, calculate the DSP output gainrequired to produce this level, G_(dsp,out)=87.15 dB_(SPL)−85.9dB_(SPL)−20.98 dBu−29.64 dB−(−19.1 dB)+11.25 dBu=−19.01 dB. In thisexample, the chirp was measured as 72.0 dB_(SPL) at 11.92 meters fromthe loudspeaker using a DSP output gain of −20.27 dB, so the calculatedoutput gain in this example was off from the actual gain by(20.27−19.01)=1.26 dB.

The procedure calculated a prescribed DSP output gain of −19.0 dB toachieve an SPL level of 72.0 dB_(SPL) at 11.9 meters from theloudspeaker, based on a single chirp measured at 1.89 m and 7.23 m froman unknown loudspeaker, and this calculated gain was in error by 1.26 dBbased on the actual measured level at 11.9 m which was positionedoutside of the two mic's range. If limited DSP resources only permitsmeasuring the level at one mic at a time in a sequential fashion, thenthe level difference (L1−L2) must be computed differently. If for eachmic, a test signal is increased until a desired SPL level is reached,and then the SPL level and output gain required is recorded, then the dBlevel difference is: dB_(diff)=(L1−G_(dBout1))−(L2−G_(dBout2)). When mic1 is closer to the speaker than mic 2, then this dB_(diff) will be apositive value. Normally L1 and L2 will be the same, but the closer micwill require a lower output gain to achieve the same SPL level for bothmics, so Gd_(Bout1) will be lower, thus giving a positive value fordB_(diff).

In another example, establishing input mic gain levels may include, ifthe microphones have known input sensitivities, then DSP input gainsincluding analog preamp gains can be set for an optimal dynamic range.For example, if the maximum sound pressure level expected in the room atthe microphone locations is 100 dB SPL, then the gain can be set so that100 dB SPL and this will provide a full-scale value. If the input gainsare set too high, then clipping may occur in the preamp or A/Dconverter. If the input gains are set too low, then weak signals andexcessive noise (distorted by automatic gain control (AGC)) will result.

If the microphones do not have known input sensitivities, then chirpresponse signal levels from loudspeakers closest to each mic input andtime-of-flight (TOF) information can be used to estimate the micsensitivities. The estimate will have errors from unknown off-axisattenuation from the loudspeakers and/or unknown off-axis attenuation ofthe mics if they do not have an omnidirectional pickup pattern, andother affects due to unknown frequency responses of the mics.

When determining loudspeaker equalization. Ideally each loudspeakerwould be equalized to compensate for its frequency responseirregularities as well as enhancement of low frequencies by nearbysurfaces. If the microphones' frequency responses are known, then eachloudspeaker response can be measured via chirp deconvolution aftersubtracting the microphones' known responses. Furthermore, if theloudspeaker has a known frequency response, then the response of justthe room can be determined. The reason for this is because surfacereflections in the room can cause comb filtering in the measuredresponse which is not desirable. Comb filtering is a time-domainphenomena and cannot be corrected with frequency-domain filtering. Thedetection of surface reflections in the impulse response must beconsidered, so that if major reflections further-out in time can bedetected, then they could be windowed-out of the impulse response andtherefore removed from the frequency response used to derive the DSPfilters.

If the microphones' frequency responses are not known, then frequencyresponse measurements cannot discriminate between irregularities due tothe loudspeaker from irregularities due to the mic. If a frequencyresponse of an unknown mic and loudspeaker were made and all thecorrection was applied to the loudspeaker output path, then deficienciesin the microphone would be over-corrected for the loudspeaker andprovide a poor sound for listeners in the far side of a room during anaudio presentation from far side speakers. Similarly, if all thecorrection was applied to the mic input path, then deficiencies in theloudspeaker would be over-corrected for the mic and would yield a poorsound for listeners at the far-end for near side speakers. “Splittingthe difference” and applying half of the correction to mic inputs andhalf to loudspeaker outputs is not a feasible strategy and is unlikelyto result in good sound.

Equalization will be applied using standard infinite impulse response(IIR) parametric filters. Finite impulse response (FIR) filters wouldnot be well suited for this application because they have a linear,rather than log or octave frequency resolution, which can require a veryhigh number of taps for low-frequency filters, and are not well suitedwhen the exact listen location(s) are not known. IIR filters aredetermined by “inverse filtering”, such that the inverse of the measuredmagnitude response is used as a target to “best-fit” a cascade ofparametric filters. Practical limits are placed on how much (dB) and howfar/wide/narrow (Hz) the auto equalization filters will correct theresponses. Frequency response correction by inverse filtering from animpulse response is known to be accurate for a source and listenerlocation. In order to make each loudspeaker sound good at all listeninglocations, since mic locations are the only know value, then frequencyresponse ensemble averaging will be performed, such that the responsefrom all microphones picked-up by a loudspeaker will be averagedtogether after some octave smoothing is applied. This procedure will betransparent to the installer because the response from all microphonescan be recorded concurrently using a single loudspeaker chirp.

One example may include a microphone equalization procedure, when themicrophone frequency response is not known, then equalization of anunknown loudspeaker is not practical and should not be attempted, andtherefore the frequency response of the unknown microphone cannot bedetermined. If, however, the loudspeakers frequency responses are known,then microphone equalization of unknown mics is possible. The process ofmic equalization via chirp deconvolution would make use of theloudspeakers' known responses stored in firmware which would besubtracted to arrive at the microphones' responses. The process shouldbe repeated for each loudspeaker so that ensemble averaging can beapplied to the measured frequency responses. Each mic's equalizersettings would be determined by inverse filtering methods as describedin loudspeaker equalization.

Once loudspeaker and microphone levels have been set and frequencyresponse irregularities have been equalized, then the speaker values andlevels can be set based on an RT60 measurements of the room. Thereverberation time (RT60) can be obtained by computing a Schroederreverse integration of the impulse, and the RT60 is a measure of howlong sound takes to decay by 60 dB in a space that has a diffusesoundfield, meaning a room large enough that reflections from the sourcereach the mic from all directions at the same level response energy.Once the RT60 value(s) is known, then NLP levels can be set wheregenerally more aggressive NLP settings are used when reverb tails arelonger than the AEC's effective tail length.

Another example may include setting output limiters. If the power ampgains are known and the loudspeaker power ratings are known, then DSPoutput limiters can be set to protect the loudspeakers. Additionally, ifthe loudspeaker sensitivities are known, then limiters could furtherreduce the maximum signal level to protect listeners from excessivesound level. Maintaining gain value information and similar records ofpower gains/sensitivities is not a feasible option for mostadministrators. Furthermore, even if the gain values were known, but thespeakers were mis-wired/misconfigured, such as in the case of incorrectbridging wiring, then the gain would be incorrect and lead to incorrectpower limiting settings. Consequently, SPL limiting is a more desirableoperation.

According to additional example embodiments, measuring a speechintelligibility rating (SIR) of a conference room may include measuringa speech transmission index (STI) in a room for one speech source to onelistener location. Alternatively, multiple speech sources, for example,ceiling speakers, and multiple listening locations around a room mayalso be examined to identify an optimal STI and corresponding SIR.Furthermore, the speech source in a conference situation may be locatedremotely, where the remote microphones, remote room, and transmissionchannel may all affect the speech intelligibility experience of thelistener. In a conference room with multiple loudspeakers, which willnormally be used concurrently, the STI should be measured with all“speech conferencing” speakers playing concurrently. Speech conferencingspeakers indicates all speakers which would normally be on during aconference, and all speakers which are dedicated to music playback wouldbe turned off. The reason is that the listener will normally belistening to speech coming out of all the speech conferencing speakersconcurrently and therefore the speech intelligibility will be affectedby all the speakers and hence the rating should be measured with all thespeech conferencing speakers active. Compared to a single loudspeaker,the STI measured with all speech conferencing loudspeakers on may bebetter or worse, depending on the background noise level, the echo andreverberation in the room, the spacing between speakers, etc.

The auto-tune process may use the microphones from the conferencingsystem and no additional measurement mics, and thus the STI measurementvalue obtained may be a proxy to the true STI value of a measurement micplaced at a listener's exact ear location. Since the conference room hasseveral listener locations, and may have several conferencing mics, themost optimal STI rating would be obtained by performing measurements atall ‘N’ mics concurrently, computing ‘N’ STI values, and then averagingthese values to give a single room a single STI value. This would be anaverage STI value measured at all conferencing mic locations which is aproxy to the average STI value at all listener locations. The auto tuneprocedure is designed to sequence through each output speaker zone oneat a time and measure all mics simultaneously. The real-time STIanalyzer task is DSP-intensive and can only measure a single mic inputat a time. Therefore, this places practical limits on measuring STIvalues at ‘N’ mics and averaging. For the most accurate STI values, allspeech conferencing speakers should be played simultaneously.Consequently, certain strategies may be necessary for possibly measuringSTI at multiple mics in the auto-tune process.

One strategy may include only measuring the STI during the first speakeriteration although all speakers play the STI signal, and measure usingthe first mic. Another approach is to measure using the mic determinedto be in a middle location as determined by the speaker-to-mic distancesmeasured in the calculation of the IR. Yet another approach is for eachspeaker zone iteration, measure STI on the next mic input so thatmultiple STI measurements can be averaged. This approach has drawbacks,such as if there is only one speaker zone, then only the first mic getsmeasured. If there are fewer speaker zones than mics, then this couldmiss the middle-located mic, and this approach takes the longest time tooperate.

It should also be noted that an STI value is normally understood torepresent the speech transmission quality in that room. For remoteconferencing systems, the speech transmission quality experienced by alistener has three components: the STI for the loudspeakers and roomhe/she is sitting in, the STI of the electronic transmission channel,and the STI of the far-end microphones and room. Therefore, the STIvalue computed by the auto-tune procedure is a proxy for just one ofthree components which make up the listeners' speech intelligibilityexperience. However, such information may still be useful as a score canbe obtained for the near-end component, of which the user or installermay have control. For example, the user/installer can use the auto-tuneSTI score to evaluate the relative improvement to the STI from using twodifferent acoustical treatment designs.

An auto equalization algorithm is capable of automatically equalizingthe frequency response of any loudspeaker in any room to any desiredresponse shape which can be defined by a flat line and/or parametriccurves. The algorithm is not designed to work in real-time during anactive program audio event, but rather during a system setup procedure.The algorithm only considers and equalizes the log magnitude frequencyresponse (decibels versus frequency) and does not attempt to equalizephase. The algorithm basically designs a set of optimal filters whosefrequency response closely matches the inverse of the measured responsein order to flatten it, or reshape it to some other desired response.The algorithm only uses single-biquad BR filters which are of type bell(boost or cut parametric filter), low-pass, or high-pass. FIR filterscould be used, but IIR filters were chosen because of theircomputational efficiency, better low-frequency resolution, and arebetter suited for spatial averaging, or equalizing over a broadlistening area in a room.

When performing the equalization process, first a desired targetfrequency response is identified. Typically, this would be a flatresponse with a low frequency roll-off and high frequency roll-off toavoid the process from designing a filter set which would be attemptingto achieve an unachievable result from a frequency-limited loudspeaker.The target mid-band response does not have to be flat, and the processpermits any arbitrary target frequency response in the form of an arrayof biquad filters. The process also permits the user to set maximum dBboost or cut limits on the total DSP filter set to be applied.

FIG. 6A illustrates a process for performing an automated tuningprocedure for an audio system. Referring to FIG. 6A, the process mayinclude identifying a plurality of separate speakers on a networkcontrolled by a controller 612, providing a first test signal to a firstspeaker and a second test signal to a second speaker 614, detecting thefirst test signal and the second test signal at one or more microphonescontrolled by the controller, and automatically establishing speakertuning output parameters based on an analysis of the different testsignals 616. The tuning parameters may be applied to a digital DSP setof parameters which are applied to the various speakers and microphonesin the audio environment.

The first test signal may be a different frequency than the second testsignal. The first test signal may be provided at a first time and thesecond test signal may be provided at a second time later than the firsttime. The process may also include automatically establishing speakertuning output parameters based on an analysis of the different testsignals by measuring an ambient noise level via the one or moremicrophones, and determining an impulse response based on the first testsignal and the second test signal, and determining a speaker outputlevel to use for the first and second speakers based on the impulseresponse and the ambient noise level. The process may also includedetermining a frequency response based on an output of the first andsecond speakers, averaging values associated with the first test signalthe second test signal to obtain one or more of an average soundpressure level (SPL) for the one or more microphones, an averagedistance from all the one or more microphones and an average frequencyresponse as measured from the one or more microphones. The process mayalso include initiating a verification procedure as an iterativeprocedure that continues for each of the first speaker and the secondspeaker. The process may also include performing an automatedequalization procedure to identify a frequency response of the first andsecond speakers to a desired response shape, and identifying one or moreoptimal filters having a frequency response that closely matches theinverse of the measured frequency response.

FIG. 6B illustrates a process for performing an automated tuningprocedure for an audio system. Referring to FIG. 6B, the process mayinclude identifying, in a particular room environment, a plurality ofspeakers and one or more microphones on a network controlled by acontroller 652, providing test signals to play sequentially from eachamplifier channel and the plurality of speakers 654, monitoring the testsignals from the one or more microphones simultaneously to detectoperational speakers and amplifier channels 656, providing additionaltest signals to the plurality of speakers to determine tuning parameters658, detecting the additional test signals at the one or moremicrophones controlled by the controller 662, and automaticallyestablishing a background noise level and noise spectrum of the roomenvironment based on the detected additional test signals 664.

The process may also include monitoring the test signals from the one ormore microphones simultaneously identifies whether any amplifier outputchannels are unconnected to the plurality of speakers. The additionaltest signals may include a first test signal being provided at a firsttime and a second test signal being provided at a second time later thanthe first time. The process may also include automatically establishinga frequency response of each of the plurality of speakers, and asensitivity level of each amplifier channel and corresponding speaker.The sensitivity level is based on a target sound pressure level (SPL) ofthe particular room environment. The process may also includeidentifying a distance from each of the one or more microphones to eachof the plurality of speakers, a room reverberation time of theparticular room environment, a per-speaker channel level setting toachieve the target SPL, a per-speaker channel equalization setting tonormalize each speaker's frequency response and to achieve a target roomfrequency response, an acoustic echo cancellation parameter that isoptimal for the particular room environment, a noise reduction parameterthat is optimal to reduce background noise detected by the microphonesfor the particular room environment, and a non-linear processingparameter that is optimal to reduce background noise when no voice isdetected for the particular room environment. The process may alsoinclude initiating a verification procedure as an iterative procedurethat continues for each of the plurality of speakers, and theverification procedure comprises again detecting the additional testsignals at the one or more microphones controlled by the controller toverify the target SPL and the target room frequency response.

FIG. 7 illustrates an example process for performing an automated audiosystem setup configuration. Referring to FIG. 7 , the process mayinclude identifying a plurality of speakers and microphones connected toa network controlled by a controller 712, assigning a preliminary outputgain to the plurality of speakers used to apply test signals 714,measuring ambient noise detected from the microphones 716, recordingchirp responses from all microphones simultaneously 718, deconvolvingall chirp responses to determine a corresponding number of impulseresponses 722, and measuring average sound pressure levels (SPLs) ofeach of the microphones to obtain a SPL level based on an average of theSPLs 724.

The measuring ambient noise detected from the microphones may includechecking for excessive noise. For each microphone input signal, theprocess may include identifying a main impulse peak, and identifying adistance from one or more of the plurality of speakers to eachmicrophone. The process may include determining frequency responses ofeach microphone input signal, and applying a compensation value to eachmicrophone based on the frequency response. The process may also includeaveraging the frequency responses to obtain a spatial average response,and performing an automated equalization of the spatial average responseto match a target response value. The process may further includedetermining an attenuation value associated with the room based on theSPL level and a distance from nearest and furthest microphones, anddetermining an output gain that provides a target sound level at anaverage distance of all microphones based on the SPL level andattenuation value.

FIG. 8 illustrates an example process for performing anauto-equalization procedure to an audio system. Referring to FIG. 8 ,the process may include determining a frequency response to a measuredchirp signal detected from one or more speakers 812, determining anaverage value of the frequency response based on a high limit value anda low limit value 814, subtracting a measured response from a targetresponse, wherein the target response is based on one or more filterfrequencies 816, determining a frequency limited target filter withaudible parameters based on the subtraction 818, and applying aninfinite impulse response (IIR) biquad filter based on an area definedby the frequency limited target filter to equalize the frequencyresponse of the one or more speakers 822.

The average value is set to zero decibels, and the target response isbased on one or more frequencies associated with one or more biquadfilters. The determining the target filter based on the target responsemay include determining target zero crossings and target filterderivative zeros. The process may also include limiting decibels of thetarget filter based on detected amplitude peaks to create a limitedfilter, and adding the limited filter to a filter set. The process mayalso include adding unlimited equalization filters to a measuredresponse to provide an unlimited corrected response. The process mayfurther include subtracting the unlimited corrected response from thetarget response to provide a new target filter.

FIG. 9 illustrates an example process for determining one or more gainvalues to apply to an audio system. Referring to FIG. 9 , the processmay include applying a set of initial power and gain parameters for aspeaker 912, playing a stimulus signal via the speaker 914, measuring afrequency response signal of the played stimulus 916, determining asound level at a microphone location and a sound level at a predefineddistance from the one or more of speakers 918, determining a gain at themicrophone location based on a difference of the sound level at themicrophone location and the sound level at the predefined distance fromthe speaker 922, and applying the gain to the speaker output 924.

The predefined distance may be a set distance associated with where auser would likely be with respect to a location of the speaker, such asone meter. The process may also include detecting the stimulus signal atthe microphone a first distance away from the speaker and at a secondmicrophone a second distance, further than the first distance, from thespeaker, and the detecting is performed at both microphonessimultaneously. The process may further include determining a firstsound pressure level at the first distance and a second sound pressurelevel at the second distance. The process may also include determiningan attenuation of the speaker based on a difference of the first soundpressure level and the second sound pressure level. The process mayfurther include determining a sensitivity of the speaker based on asound pressure level measured at a predefined distance from the speakerwhen the speaker is driven by a reference voltage.

FIG. 10 illustrates a process for identifying a speech intelligibilityrating or speech transmission index. Referring to FIG. 10 , the processmay include initiating an automated tuning procedure 1012, detecting viathe one or more microphones a sound measurement associated with anoutput of a plurality of speakers at two or more locations 1014,determining a number of speech transmission index (STI) values equal toa number of microphones 1016, and averaging the speech transmissionindex values to identify a single speech transmission index value 1018.

The process may also include measuring the number of STIs values while aplurality of speakers are concurrently providing output signals. Themeasuring the number of STIs values while a plurality of speakers areconcurrently providing output signals may include using one microphone.The measuring the number of STIs values while a plurality of speakersare concurrently providing output signals may include using onemicrophone among a plurality of microphones and the one microphone isidentified as being closest to a middle location among locations of theplurality of speakers. The averaging the speech transmission indexvalues to identify a single speech transmission index value may includemeasuring the STI values at ‘N’ microphones, and ‘N’ is greater thanone, and averaging the ‘N’ values to identify a single STI value for aparticular environment.

The automated tuning may automatically measure the speechintelligibility of the conferencing audio system and the correspondingroom, using only the components normally needed by the conferencingsystem, and no other instrumentation. The automated tuning may be usedwith 3rd-party power amplifiers and loudspeakers. Since the gain andsensitivity of these components are unknown, the auto tune processrapidly determines these parameters using a unique broad-band multitoneramp-up signal until it has reached a known SPL level at themicrophones, along with speaker-to-microphone distances measuredautomatically via acoustic latency and calculated using the speed ofsound. Using this technique, auto tune can determine the gain andsensitivity of the corresponding components, and the SPL level from theloudspeaker. Ramping up a broadband multitone signal rapidly, and forthe automatic determination of the system parameters providesoptimization. The auto tune auto-equalization algorithm rapidlyequalizes multiple speaker zones, based on the various filters. Also,additional enhancements are added to that algorithm.

The process may include analyzing an electro-acoustic sound system interms of levels and gains to determine gains required to achieve desiredacoustic levels, as well as to optimize the gain structure for maximumdynamic range. Sound pressure level is historically expressed in “dBSPL”. Sound levels are often expressed with units of “dB” where it isimplied that it is actually an absolute level relative to 0 dB=20 uPascal. Modern international standards express sound pressure level asLp/(20 uPa) or shortened to Lp. However Lp is also commonly used todenote a variable in sound level rather than the unit of sound level. Toavoid any confusion, in this analysis the sound pressure level willalways be expressed as “dBa” meaning absolute acoustic level and is thesame thing as the outdated “dB SPL”. “dBa” should not be confused with“dBA” which often is the units expressed for A-weighted sound levels. Inthis analysis, ‘L’ is always a level variable which is an absolutequantity, and ‘G’ is always a gain variable which is a relativequantity. Since the equations contain variables having different units(electrical versus acoustical), while still being in decibels, the unitsare shown explicitly in { } for clarity.

The analysis is broken into two distinctly different signal paths, theinput path from an acoustic source (talker 218) to the DSP internalprocessing, and the path from the DSP internal processing to theacoustic level output from the loudspeaker. These two paths then eachhave two variations. The input signal path has an analog versus digitalmic variation, and the output path has an analog versus digital poweramp variation (digital in terms of its input signal, not its poweramplification technology). For the sake of consistency and simplicity,all signal attenuations are expressed as a gain which would have anegative value. For example, GP-S=LP−LSpkr is the gain from theloudspeaker (@ 1 meter) to the person, and this value might be somethinglike −6 dB. These gains are shown as direct arrows in the illustration,but in reality the sound path consists of surface reflections anddiffuse sound from around the room. Clearly the impulse response of theroom would reveal details of the room behavior, but in this analysis weare only concerned with non-temporal steady-state sound levels, forexample resulting from pink noise. For simplicity in this analysis thesemultiple sound paths are all lumped into a single path with gain ‘G’. Bymeasuring GP-S and GM-P, a known sound level at the listener positioncan be identified, as well as a set DSP output gain and input preampgains. Since there is no measurement microphones at the listenerposition, GP-S and GM-P are estimates. However, we can accuratelymeasure GM-S and make some estimates of GP-S and GM-P based on typicalconference room acoustics “rules-of-thumb”. For the sake of consistencyand simplicity, all signal attenuations are expressed as a gain whichwould have a negative value. For example, GP-S=LP−LSpkr is the gain fromthe loudspeaker (@ 1 meter) to the person, and this value might besomething like −6 dB. These gains are shown as direct arrows in theillustration, but in reality the sound path consists of surfacereflections and diffuse sound from around the room. Clearly the impulseresponse of the room would reveal details of the room behavior, but inthis analysis the non-temporal steady-state sound levels are identified,for example resulting from pink noise. For simplicity in this analysisthe multiple sound paths are all lumped into a single path with gain G.GP-S and GM-P are measured so a known sound level at the listenerposition can be identified, as well as set DSP output gain and inputpreamp gains optimally.

The automated tuning may automatically measure the speechintelligibility of the conferencing audio system and the correspondingroom, using only the components normally needed by the conferencingsystem, and no other instrumentation. The automated tuning may be usedwith 3rd-party power amplifiers and loudspeakers. Since the gain andsensitivity of these components are unknown, the auto tune processrapidly determines these parameters using a unique broad-band multitoneramp-up signal until it has reached a known SPL level at themicrophones, along with speaker-to-microphone distances measuredautomatically via acoustic latency and calculated using the speed ofsound. Using this technique, auto tune can determine the gain andsensitivity of the corresponding components, and the SPL level from theloudspeaker. Ramping up a broadband multitone signal rapidly, and forthe automatic determination of the system parameters providesoptimization. The auto tune auto-equalization algorithm rapidlyequalizes multiple speaker zones, based on the various filters. Also,additional enhancements are added to that algorithm.

One example embodiment may include measuring speech intelligibility toreasonably obtain a speech intelligibility rating for a conference room.The speech transmission index (STI) should be identified with respect tomultiple speech sources (for example ceiling speakers), and multiplelistening locations around the room. Furthermore, the speech source in aconference situation may be located remotely, where the remotemicrophones, remote room, and transmission channel may all affect thespeech intelligibility experience of the listener. In a conference roomwith multiple loudspeakers which will normally be used concurrently, theSTI logically should be measured with all “speech conferencing” speakersplaying concurrently. Speech conferencing speakers means all speakerswhich would normally be on during a conference, and all speakers whichare dedicated to music playback would be turned off. The reason is thatthe listener will normally be listening to speech coming out of all thespeech conferencing speakers concurrently and therefore the speechintelligibility will be affected by all the speakers and hence therating should be measured with all the speech conferencing speakersturned on. Compared to a single loudspeaker, the STI measured with allspeech conferencing loudspeakers on may be better or worse, depending onthe background noise level, the echo and reverberation in the room, thespacing between speakers etc.

Since auto tune must use the microphones from the conferencing systemand not additional measurement mics, then it should be noted that theSTI measurement value from Auto Tune is a proxy to the true STI value ofa measurement mic placed at a listener's ear location. Since theconference room has several listener locations, and may have severalconferencing mics, the best STI rating would be obtained by measuring atall N mics concurrently, compute N STI values, and then average thesevalues to give a single room STI value. This would be an average STIvalue measured at all conferencing microphone locations which would inturn be a proxy to the average STI value at all listener locations. Theauto tune algorithm(s) are designed to sequence through each outputspeaker zone one at a time and measures all microphones simultaneously.Furthermore, the real-time STI analyzer task is very DSP-intensive andcan only measure a single microphone input at a time. Therefore, thisplaces practical limits on measuring STI values at ‘N’ microphones andaveraging the values. For the most accurate STI values, all speechconferencing speakers should be played simultaneously.

A few strategies for possibly measuring STI at multiple microphones inan auto tune procedure may include, as a first approach, only measuringSTI during the first speaker iteration but all speakers will play theSTIPA, and then the measurement is performed using the first microphonebut measurements using the microphone are determined to be in a middlelocation as determined by the speaker-to-microphone distances measuredin the CalcIR state. Another approach may include, for each speaker zoneiteration, measuring an STI on the next microphone input so thatmultiple STI measurements can be averaged. However, certain concerns maybe if there is only one speaker zone, then only the first microphonewill be measured. If there are fewer speaker zones than microphones,then the middle-located microphone could be missed and this approachtakes the longest to run.

It should also be noted that an STI value is normally understood torepresent the speech transmission quality in that room. For remoteconferencing systems, the speech transmission quality experienced by alistener actually has three components the STI for the loudspeakers androom a person is sitting in, the STI of the electronic transmissionchannel and the STI of the far-end microphones and room. Therefore, theSTI value computed by auto-tune is a proxy for just one of threecomponents which make up the listeners speech intelligibilityexperience. However, this may still provide a score for the near-endcomponent, which the user or installer may have control of during theevent. For example, the user/installer can use the auto tune STI scoreto evaluate the relative improvement to STI from using two differentacoustical treatment designs.

The automated tuning may automatically measure the speechintelligibility of the conferencing audio system and the correspondingroom, using only the components normally needed by the conferencingsystem, and no other instrumentation. The automated tuning may be usedwith 3rd-party power amplifiers and loudspeakers. Since the gain andsensitivity of these components are unknown, the auto tune processrapidly determines these parameters using a unique broad-band multitoneramp-up signal until it has reached a known SPL level at themicrophones, along with speaker-to-microphone distances measuredautomatically via acoustic latency and calculated using the speed ofsound. Using this technique, auto tune can determine the gain andsensitivity of the corresponding components, and the SPL level from theloudspeaker. Ramping up a broadband multitone signal rapidly, and forthe automatic determination of the system parameters providesoptimization. The auto tune auto-equalization algorithm rapidlyequalizes multiple speaker zones, based on the various filters. Also,additional enhancements are added to that algorithm.

The operations of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in acomputer program executed by a processor, or in a combination of thetwo. A computer program may be embodied on a computer readable medium,such as a storage medium. For example, a computer program may reside inrandom access memory (“RAM”), flash memory, read-only memory (“ROM”),erasable programmable read-only memory (“EPROM”), electrically erasableprogrammable read-only memory (“EEPROM”), registers, hard disk, aremovable disk, a compact disk read-only memory (“CD-ROM”), or any otherform of storage medium known in the art.

FIG. 11 is not intended to suggest any limitation as to the scope of useor functionality of embodiments of the application described herein.Regardless, the computing node 1100 is capable of being implementedand/or performing any of the functionality set forth hereinabove.

In computing node 1100 there is a computer system/server 1102, which isoperational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 1102 include, but are notlimited to, personal computer systems, server computer systems, thinclients, rich clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 1102 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 1102 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As displayed in FIG. 11 , computer system/server 1102 in cloud computingnode 1100 is displayed in the form of a general-purpose computingdevice. The components of computer system/server 1102 may include, butare not limited to, one or more processors or processing units 1104, asystem memory 1106, and a bus that couples various system componentsincluding system memory 1106 to processor 1104.

The bus represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 1102 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 1102, and it includes both volatileand non-volatile media, removable and non-removable media. System memory1106, in one embodiment, implements the flow diagrams of the otherfigures. The system memory 1106 can include computer system readablemedia in the form of volatile memory, such as random-access memory (RAM)1110 and/or cache memory 1112. Computer system/server 1102 may furtherinclude other removable/non-removable, volatile/non-volatile computersystem storage media. By way of example only, storage system 1114 can beprovided for reading from and writing to a non-removable, non-volatilemagnetic media (not displayed and typically called a “hard drive”).Although not displayed, a magnetic disk drive for reading from andwriting to a removable, non-volatile magnetic disk (e.g., a “floppydisk”), and an optical disk drive for reading from or writing to aremovable, non-volatile optical disk such as a CD-ROM, DVD-ROM or otheroptical media can be provided. In such instances, each can be connectedto the bus by one or more data media interfaces. As will be furtherdepicted and described below, memory 1106 may include at least oneprogram product having a set (e.g., at least one) of program modulesthat are configured to carry out the functions of various embodiments ofthe application.

Program/utility 1116, having a set (at least one) of program modules1118, may be stored in memory 1106 by way of example, and notlimitation, as well as an operating system, one or more applicationprograms, other program modules, and program data. Each of the operatingsystem, one or more application programs, other program modules, andprogram data or some combination thereof, may include an implementationof a networking environment. Program modules 1118 generally carry outthe functions and/or methodologies of various embodiments of theapplication as described herein.

As will be appreciated by one skilled in the art, aspects of the presentapplication may be embodied as a system, method, or computer programproduct. Accordingly, aspects of the present application may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present application may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Computer system/server 1102 may also communicate with one or moreexternal devices 1120 such as a keyboard, a pointing device, a display1122, etc.; one or more devices that enable a user to interact withcomputer system/server 1102; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 1102 to communicate withone or more other computing devices. Such communication can occur viaI/O interfaces 1124. Still yet, computer system/server 1102 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 1126. As depicted, network adapter1126 communicates with the other components of computer system/server1102 via a bus. It should be understood that although not displayed,other hardware and/or software components could be used in conjunctionwith computer system/server 1102. Examples include, but are not limitedto: microcode, device drivers, redundant processing units, external diskdrive arrays, RAID systems, tape drives, and data archival storagesystems, etc.

One skilled in the art will appreciate that a “system” could be embodiedas a personal computer, a server, a console, a personal digitalassistant (PDA), a cell phone, a tablet computing device, a smartphoneor any other suitable computing device, or combination of devices.Presenting the above-described functions as being performed by a“system” is not intended to limit the scope of the present applicationin any way but is intended to provide one example of many embodiments.Indeed, methods, systems and apparatuses disclosed herein may beimplemented in localized and distributed forms consistent with computingtechnology.

It should be noted that some of the system features described in thisspecification have been presented as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom verylarge-scale integration (VLSI) circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A module may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, graphics processing units, or thelike.

A module may also be at least partially implemented in software forexecution by various types of processors. An identified unit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions that may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module. Further, modules may bestored on a computer-readable medium, which may be, for instance, a harddisk drive, flash device, random access memory (RAM), tape, or any othersuch medium used to store data.

Indeed, a module of executable code could be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork.

It will be readily understood that the components of the application, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations.Thus, the detailed description of the embodiments is not intended tolimit the scope of the application as claimed but is merelyrepresentative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that theabove may be practiced with steps in a different order, and/or withhardware elements in configurations that are different than those whichare disclosed. Therefore, although the application has been describedbased upon these preferred embodiments, it would be apparent to those ofskill in the art that certain modifications, variations, and alternativeconstructions would be apparent.

While preferred embodiments of the present application have beendescribed, it is to be understood that the embodiments described areillustrative only and the scope of the application is to be definedsolely by the appended claims when considered with a full range ofequivalents and modifications (e.g., protocols, hardware devices,software platforms etc.) thereto.

What is claimed is:
 1. A method, comprising: determining a frequencyresponse to a measured chirp signal detected from one or more speakers;determining an average value of the frequency response based on a highlimit value and a low limit value; subtracting a measured frequencyresponse from the one or more speakers from a target response, whereinthe target response is based on one or more filter frequencies;determining a frequency limited target filter with audible parametersbased on the subtraction; and applying an infinite impulse response(IIR) biquad filter based on an area defined by the frequency limitedtarget filter to equalize the frequency response of the one or morespeakers.
 2. The method of claim 1, wherein the average value is set tozero decibels.
 3. The method of claim 1, wherein the target response isbased on the one or more frequencies associated with one or more biquadfilters.
 4. The method of claim 3, wherein the determining the targetfilter based on the target response comprises determining target zerocrossings and target filter derivative zeros.
 5. The method of claim 1,comprising limiting decibels of the target filter based on detectedamplitude peaks to create a limited filter; and adding the limitedfilter to a filter set.
 6. The method of claim 5, comprising addingunlimited equalization filters to the measured response to provide anunlimited corrected response.
 7. The method of claim 6, comprisingsubtracting the unlimited corrected response from the target response toprovide a new target filter.
 8. An apparatus, comprising: a processorconfigured to determine a frequency response to a measured chirp signaldetected from one or more speakers; determine an average value of thefrequency response based on a high limit value and a low limit value;subtract a measured frequency response from the one or more speakersfrom a target response, wherein the target response is based on one ormore filter frequencies; determine a frequency limited target filterwith audible parameters based on the subtraction; and apply an infiniteimpulse response (IIR) biquad filter based on an area defined by thefrequency limited target filter to equalize the frequency response ofthe one or more speakers.
 9. The apparatus of claim 8, wherein theaverage value is set to zero decibels.
 10. The apparatus of claim 8,wherein the target response is based on the one or more frequenciesassociated with one or more biquad filters.
 11. The apparatus of claim10, wherein the target filter is determined based on the target responseby the processor being configured to determine target zero crossings andtarget filter derivative zeros.
 12. The apparatus of claim 8, whereinthe processor is further configured to limit decibels of the targetfilter based on detected amplitude peaks to create a limited filter; andadd the limited filter to a filter set.
 13. The apparatus of claim 12,wherein the processor is further configured to add unlimitedequalization filters to the measured response to provide an unlimitedcorrected response.
 14. The apparatus of claim 13, wherein the processoris further configured to subtract the unlimited corrected response fromthe target response to provide a new target filter.
 15. A non-transitorycomputer readable storage medium configured to store instructions thatwhen executed cause a processor to perform: determining a frequencyresponse to a measured chirp signal detected from one or more speakers;determining an average value of the frequency response based on a highlimit value and a low limit value; subtracting a measured frequencyresponse from the one or more speakers from a target response, whereinthe target response is based on one or more filter frequencies;determining a frequency limited target filter with audible parametersbased on the subtraction; and applying an infinite impulse response(IIR) biquad filter based on an area defined by the frequency limitedtarget filter to equalize the frequency response of the one or morespeakers.
 16. The non-transitory computer readable storage medium ofclaim 15, wherein the average value is set to zero decibels.
 17. Thenon-transitory computer readable storage medium of claim 15, wherein thetarget response is based on the one or more frequencies associated withone or more biquad filters.
 18. The non-transitory computer readablestorage medium of claim 17, wherein the determining the target filterbased on the target response comprises determining target zero crossingsand target filter derivative zeros.
 19. The non-transitory computerreadable storage medium of claim 15, wherein the processor is furtherconfigured to perform: limiting decibels of the target filter based ondetected amplitude peaks to create a limited filter; and adding thelimited filter to a filter set.
 20. The non-transitory computer readablestorage medium of claim 19, wherein the processor is further configuredto perform: adding unlimited equalization filters to the measuredresponse to provide an unlimited corrected response; and subtracting theunlimited corrected response from the target response to provide a newtarget filter.